<!doctype html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>
<style>
    #warpper{
        height:500px;
    }
    #content{
        height: 100%;
        background: lightcoral;
    }
</style>

<div id="warpper">
    <div id="content">
        dsfdsf
    </div>
</div>
</body>
</html>